1. Field of Invention
The present invention relates to a gas generator used in a restraining device installed in a vehicle and the like.
2. Description of Related Art
Gas generators used in air bag systems or the like and, in particular, gas generators that use a solid gas generating agent as an operative gas source, adopt a structure for controlling inner combustion pressure in order to finely adjust output performance. Even with a same gas generator, sometimes output pressure differs particularly depending on an environmental temperature at activation of the gas generator. This is because a burning rate (reaction rate) of a gas generating agent varies depending on the environmental temperature and, generally, the higher the temperature is, the faster the combustion becomes. Here, an environmental temperature refers to a temperature according to season, region, a state of a vehicle (for example, whether the vehicle is parked in a shade or under the sun), and the like.
Attempts are being made to suppress a variation in output pressure due to a difference in such environmental temperatures.
FIG. 3 in JP-A No. 6-183310 shows a gas generator 22 with an elongated housing. A large-diameter orifice 26 and a small-diameter orifice 28 are formed at two locations that face each other on a peripheral wall of a housing 24 and are respectively closed by foils 32. In addition, intermediate-diameter orifices 34 are formed at equal intervals in the circumferential direction at an end portion of the housing 24, and the intermediate-diameter orifices 34 are closed by foils 36 that are thicker than the foils 32.